Partially we are talking about different age groups. I was no longer playing dollhouse at ages 10-12. (well, Maybe at age 10 but not by age 12) I had moved on to programming (in Basic -- We had a Kaypro computer and at the end of that time I got a Commodore 64 of my very own), Making my own robot from a kit, etc. I don't think I was doing much with dolls at all. We made up skits from music we liked and put them on for family and occasionally visiting friends. We played board games. I wrote stories in the Star Trek universe (TOS) and the Batman and Robin TV-show universe. I think my Lego days were mostly behind me at that time too. Though I did play with Star Wars figures when younger -- a friend of ours had them -- but we pretty much played the same way I talked about above with dollhouse figures. We were not trying for accuracy (I'm not even sure we knew the REAL Star Wars story at the time -- early 1980s.. The figures were just cool)

"hopping" That's a good way to describe how characters move. IF we physically moved them a step at a time.
I think it could also be termed "flying" -- Unless you have a car to put them in. Then the car Zooms across the floor. (but if the destination is on a table/bed, there is equal chances of the car "driving" up the leg or having a quick flying jaunt to the destination)
We didn't have doll house cars, so we would put all the people in a shoe box and then move that shoe box to the house in the other room -- the shoebox was the "car" (And no, we didn't put wheels on it or decorate it like a car or anything. Think of a fairy godmother. *tap" and it is a car. *tap* and it turns back into shoebox/general storage for whatever is needed.

They do not have any less movement than the doll house figures I played with endlessly growing up. IT never even occurred to me to wish they had more movement. Nor did it prevent me from spending hours having them go visit my sister's family and her house, or playing my own house. I think a figure the target aged girl can identify with is much more important than movement.
My own daughter (age 5) plays more with the animal figures as the main characters in her stories -- and they do not move at all!

As you said, for the target market, I don't think the different sizes is an issue at all.
I see my son and daughter playing with their Lego together. It is never a problem if the figure they are holding is a minifigure or a minidoll.
I remember the play I did as a child. I would put families together of dollhouse figures and minifigures for the "toddlers" (even though they were out of proportion) and we would act out the Christmas story using every toy that could come to hand -- the angel was always the ceramic decorative angel on the wall. But some figures would be Little People while others would be brick-built people or Barbies. Just depended on what we were playing with that year. I remember the year we used a Hot Wheels car as the "Camel" to carry Mary and Joseph to the stable. And baby Jesus would usually be one of our baby dolls so we could cuddle him ourselves. (So massively bigger in scale than all the other people)

I have two kids -- ages 5 and 9. WHen we went on vacation this summer, I carried their Lego passports with me in my purse to check out every Lego store we might run into. I wonder, should we manage to get London before they are too old, if the London Lego store would be able to stamp their blue passport books? Or if there is some difference inside (Usually a store only has 1 stamp to give at a time. But the stamps change over time, to incentize coming back)
I LOVE that red Double Decker Bus I saw in the background of your pictures. I had a red bus like that as a kid (Hot Wheels type. Not sure where I got it -- maybe Florida's Disney?) but have been fond ever since. Not that they are easy to find over here. I got a freebie double decker bus from Lego a while back with purchase but had no idea it was available as a purchaseable set now!

I like Olivia's original Workshop better -- with the microscope, clamp, chemicals, etc. (I still have it set up in my office to look at frequently) But I do like the extra robots and robot charging spots on this one.
I LOVE the photography set. Reminds me of my dad's set up. May need to get two to have two of those lights (or see if I have the pieces to put it together already)
I didn't like a bunny in the bakery set. Animals and food do not mix!
I also like Andrea's stage set better than this new one -- esp. the piano.
The puppy sets... My 5 year old will love. She doesn't care what the set itself is. The pieces will go in the bin with other Lego pieces. But the Dogs will get added to her animal collection and played with plenty. We can afford $6 for just the animal piece. The puppy car may well find itself with a whole menagerie inside.
I really like this pool better than the last one. ESP the new slide pieces that will allow for much more variation in slides in the future! And an aquarium! And the stairs! And a lifeguard seat! I do miss the basketball hoop where you played from the pool.